Immunochemical changes in the maturing (neonate through adult) mouse kidney will be evaluated for their reactivity to specific antisera. Specifically this will employ antistreptococcal cell membrane (SCM), anti human and anti mouse glomerular basement membrane (GBM) sera obtained from previous studies and whose specificities have been characterized. Thus, localization of antibody, as detected by fluorescent techniques, on kidney sections within age grouping could be correlated to specificity of the antisera, thereby defining the immunochemical properties of the antigenic site. These studies include both in vitro and in vivo experiments and it is hoped that the in vivo studies will elucidate the manner in which any immunologic deposits are recognized. The in vivo tissue evaluations include both fluorescent antibody analyses as well as electron microscopy. Strains of animals or age groupings which show significant immunological variations, for example a change with tissue from a positive reaction to a negative one, will be further characterized biochemically. Here attempts will be made to isolate the GBM and compare early to late GBM compositions for carbohydrate and protein content. Additionally attempts at peptide analysis will be undertaken to identify the antigen specific peptide.